Apparatus for grinding

ABSTRACT

THE INVENTION RELATES TO A GRINDING MACHINE HAVING A WHEEL TRUING DEVICE MOUNTED ON THE GRINDING MACHINE TABLE THAT SUPPORTS THE WORKPIECE WITH A MECHANISM FOR RAISING OR LOWERING THE TRUING TOOL OF THE DEVICE AND HAVING AN INDICATING COUNTER CONNECTED WITH THE DRIVING MECHANISM TO INDICATE THE ELEVATION OF THE TRUING TOOL. THE GRINDING WHEEL ALSO HAS A MECHANISM FOR MOVING IT VERTICALLY AND HAS A COUNTER CONNECTED WITH THE MECHANISM TO INDICATE THE ELEVATION OF THE GRINDING WHEEL. BOTH OF THE COUNTERS ARE DRIVEN THROUGH CLUTCH DEVICES THAT WILL PERMIT ADJUSTMENT OF THE COUNTERS RELATIVE TO EACH OTHER SO THAT THE ABSOLUTE POSITION OF THE GRINDING WHEEL RELATIVE TO THE SURFACE TO BE GROUND THEREBY CAN BE INDICATED ON ITS COUNTER.

Sept. 21, 1971 F. a. KRAFFT ETAL 3,606,703

APPARATUS FOR GRINDING Filed May 12, 1969 INVENTORS FREOERlCK C1. KRRFFT BY WILURM (1. BRLDENHOPER MAM United States Patent O1 hoe 3,605,703 Patented Sept. 21, 1971 3,606,703 APPARATUS FOR GRINDING Frederick G. Kraift, 2975 Fox Hollow Road, and William v G. Baldenhofer, 4222 Grant Road, both of Springfield,

Ohio 45502 Filed May 12, 1969, Ser. No. 823,788 Int. Cl. B24b 49/18 US. 'Cl. 51-165 11 Claims ABSTRACT OF THE DISCLOSURE The invention relates to a grinding machine having a wheel truing device mounted on the grinding machine table that supports the workpiece with a mechanism for raising or lowering the truing tool of the device and having an indicating counter connected with the driving mechanism to indicate the elevation of the truing tool. The grinding wheel also has a mechanism for moving it vertically and has a counter connected with the mechanism to indicate the elevation of the grinding wheel. Both of the counters are driven through clutch devices that will permit adjustment of the counters relative to each other so that the absolute position of the grinding wheel relative to the surface to be ground thereby can be indicated on its counter.

The present invention relates to an apparatus for grinding and is particularly concerned with such an arrangement utilizing a grinding wheel truing or dressing tool, and wherein size control of the workpiece is automatically accomplished.

.The combination of grinding wheels and Wheel dressers or truing tools is known and likewise an arrangement is known wherein an indicating mechanism, such as a digital display or counter, shows the position of the wheel and is compensated when the wheel is dressed or true. The present invention represents a refinement and improvement in this general type of arrangement, and wherein the size of the workpiece is controlled automatically by the manner in which the wheel dresser or truing tool is adjusted and the manner in which the down feed of the wheel into the workpiece is accomplished.

OBJECTS OF THE INVENTION machine having a wheel truing tool associated therewith,-

wherein the truing tool trues the wheel by engagement therewith on the same side of the wheel that engages the workpiece.

- Another object of this invention is the provision of an arrangement for truing a grinding wheel in which the adjustment of the truing tool slide is made reliable for a long period of time.

A still further object of the invention is the provision of an arrangement in a grinding machine having vertical feed-mechanism for the grinding wheel and a counter connected thereto in which adjustments can readily be made for reduction in wheel size as the wheel wears or is reduced in size through truing.

A still further object of this invention is the provision of a grinding wheel arrangement, including a wheel truing device, in which the operation of the machine is simplified and the operator is freed from making calculations with regard to work height or stock removal.

Still another object of this invention is the provision of a grinding machine arrangement having an economical drive device to the wheel head for moving the wheel head vertically and which will permit rapid movement of the wheel head and also reduce speed movement during feed.

It is also an object of the present invention to provide for the digital display of the movement of pulse feed and a mechanism to actuate the display device.

A further object of the present invention is the provi sion of a digital display arrangement and a drive therefor which can count at an extremely rapid rate.

The foregoing objects, as well as still other objects and advantages, will become more apparent upon reference to the following detailed specification, taken in connection with the accompanying drawings, in which:

FIG. 1 is a somewhat schematic view of a typical grinding machine adapted for practicing the present invention; and

FIG. 2 is a diagrammatic showing of the operative components making up the present invention.

BRIEF SUMMARY OF THE INVENTION In a grinding machine, according to the present invention, there is a reciprocating table on which a workpiece is mounted on a suitable chuck mechanism for being operated by a grinding wheel carried on a wheel head that is vertically moveable on the frame of the grinding machine. A precision elevating screw in the frame of the grinding machine is connected to the wheel head to move it vertically. This precision screw is connected through a drive train with a reversible hydraulic motor so that the control of fluid to the motor will cause movement of the wheel upwardly or downwardly.

A counter mechanism of special design is connected to the drive train leading from the fiuid motor and is operable for indicating movements of the wheel of as little as one ten-thousandth of an inch (0.0001) in the vertical direction. The special counter mechanism also includes other indicating wheels, preferably decimal wheels, so that the absolute position of the grinding wheel at all times can readily be read from the counter. A multiple position positive drive clutch is interposed between the counter and the drive train to permit adjustment of the counter to compensate for reduction in wheel diameter and to permit setting of the counter when the machine is first set up.

A feature of the counter is the extremely high rate at which counts can be accumulated, up to 200,000 counts per minute.

Mounted on the table of the grinding machine is a truing device comprising a slide on which the truing tool is mounted with a precision screw for moving the truing tool slide vertically. A second drive train leads from a second hydraulic motor to this last mentioned screw and connected to the drive train by way of another multiple position clutch is a second counter so graduated as to indicate movement of the truing tool in increments of one ten-thousandth of an inch (0.0001").

In operation, the truing tool may be set to the level that the workpiece on the table is to be finished. The grinding wheel is then brought down on the truing tool from above and a truing operation carried out thereon at the same point on the grinding wheel that will engage the work.

When the truing operation is completed, the counter for the grinding wheel is adjusted so that it conforms to the reading on the counter for the dressing tool and which, in turn, has been adjusted to show exactly the height of the truing tool above the chuck surface. Thereafter, the wheel is elevated from the truing tool, and iS' DETAILED DESCRIPTION Referring to the drawings somewhat more in detail, a grinding machine embodying the present invention is shown in FIG. 1, and comprises a bed on which a table 12 is reciprocably mounted. Table 12 carries a chuck 14 on which the workpiece to be machined is mounted. Positioned over table 12 is a grinding wheel 16, which is carried by a Wheel head, generally indicated at 18, and which includes a drive motor for driving the wheel in rotation. Wheel head 18 is vertically reciprocable on the frame part 2.0 of the grinding machine, which may be integral with or attached to bed 10.

Supported on table '12, toward one end thereof, is a truing tool mechanism, indicated at .22, and which is adapted for engagement with the grinding wheel for carrying out a truing operation thereon. As will be seen, the truing tool is adapted for engaging the wheel from directly therebeneath, which is the same region of the wheel that engages the workpiece. By so engaging the wheel from the bottom, the wheel is dressed round and the counter connected to the wheel elevating mechanism to indicate the wheel position will give an absolute reading. Furthermore, even if the wheel spindle moves in a slight orbit, truing at the bottom of the wheel, according to the present invention, will produce a wheel which is dressed true with respect to the finished work plane. Orbiting of the wheel center may occur due to hearing or spindle run-out, or to wheel unbalance or other similar causes. If, for instance, the wheel spindle is moving in an orbit (usually not truly circular because of the shape of the supporting structure, or because of the angle of the force which is producing the orbit) the wheel will actually be dressed out of round so that the periphery of the wheel moves in an exact path at its point of engagement with the dressing tool which is also its point of engagement with the work.

Turning now to FIG. 2, the truing device 22 will be seen to comprise a frame part 24 resting on table '12 and fixed thereto, and within which frame there is slidably mounted a slide 26 that carries the truing tool proper is driven by worm 34 mounted on a shaft together with a second worm wheel 36 which, in turn, is driven by a worm 38.

Worm 38 is mounted on a shaft 40 connected to a reversible, variable speed motor 42, such as a fluid motor, which can be reversibly supplied with fluid from a reversing valve 44, and which also has a central position wherein motor 42 is free to be manually rotated. Shaft 40 is connected with a counter 46 via a plate 48 connected to the counter and having ten circumferential holes 50 therein adapted for selectively receiving bolt 52 carried in drive arm 54, which is connected to shaft 40.

The Worms and worm wheels 32, 34, 36, 38 between shaft 40 and precision screw 30* provide for such a reduction in speed from shaft 40 to screw 30 that one rotation of shaft 40 will produce one-thousandth of an inch (0.001) travel of slide 26. The counter 46 is arranged so that its right hand digit wheel will rotate in unison with shaft 40 and will, therefore, indicate one ten-thou- 4 sandth of an inch (00001) of movement of slide 26. By the provision of plate 48 with its ten holes 50, counter 46 can be adjusted relative to shaft 40 to indicate the exact position of truing tool 28 above the surface of chuck 14.

In FIG. 2, the required finished work height above the surface of chuck 14 is indicated at X. After initially setting the truing tool 28 to exactly the chuck height, and then, by availing of the clutch consisting of bolt 52 and disc 48, counter 46 is disengaged from the shaft 40 and adjusted to read 0.0000. The truing tool 28 is elevated by means of motor 42 and control 44 until truing tool 28 is exactly the same level as the level desired for the finished workpiece. (As will be explained hereinafter, a slightly diflerent setting for the truing tool may be employed if so desired.) Assuming, however, that the truing tool is set at exactly the level of a finished workpiece, when the grinding wheel 16 is trued by the truing tool, the level of the lowermost part of the grinding wheel will also be at the level of the finished workpiece.

The wheel head 18 is also connected with a precision elevating screw 60 which, in turn, is connected to a worm wheel 62 engaged by a worm 64. Worm 64 is mounted on a shaft together with another worm wheel 66, which is engaged by a worm 68. Worm 68 is mounted on a shaft 70 which is connected for being driven by a reversible hydraulic motor 72, to which fluid is reversibly supplied by a reversing valve 74, which also has a center position wherein motor '72 is halted, and/ or may be man ually operated.

Shaft 70 is connected to another shaft 76 by a clutch arrangement consisting of a 100 tooth gear 78 on each of shafts 70 and 76. There is a 100 tooth sleeve 80' normally engaging both of the gears, but retractable from engagement with one thereof by moving it against the bias of a spring 83'. Shaft 76 is connected with a disc 82, which has graduations, indicated at 84, on the periphery thereof and arranged in successive groups, numbered from zero to nine.

The drive reduction provided by the worms 64, 68 and worm whels 66, 62 is such that one revolution of shaft 70 will produce one 100th of an inch of movement (0.01") in the vertical direction of wheel head 18. Inasmuch as disc 82 has 100 uniformly spaced graduations thereon, it will be evident that each graduation will correspond to one ten-thousandth of an inch (0.0001") of movement of wheel head 18.

Disc 82 is furthermore provided with 20 depressions or finger holes 86 in the face thereof by means of which the disc can be rotated to provide for manual raising and lowering of Wheel head 18. The angular distance between adjacent ones of the finger holes 86 will provide for five ten-thousandths of an inch (0.000 5) of movement of the wheel head so that the operator of the machine can, by tactile sense and without observing the disc 82, determine quite closely the amount of travel imparted to the wheel head by rotation of disc 82.

The disc 82, in effect, forms the first wheel of a counter mechanism, which also comprises the counter unit at 88, which has therein a plurality of decimal digit wheels 90. The input to counter 88 is connected by a slip-free drive, such as a chain or cog belt, 92 at a one to one ratio with shaft 7 6. One rotation of shaft 76 will cause one rotation of the right hand digit wheel or counter 88 and which Wheel, since it is graduated from zero to nine, will indicate one-thousandth of an inch (0.001") of movement of wheel head 18 Shaft 70 also has associated therewith an automatic downfeed mechanism 94, which may be of a conventional type. Downfeed mechanism 94 is normally disengaged from shaft 70, but when the downfeed mechanism is made operative it will index shaft 70 in a direction to feed wheel head 18 downwardly in small increments of movement. The exact amount of travel imparted to the wheel head each time the downfeed mechanism operates is under the control of an adjusting wheel 96, which can provide for increments of feed of the wheel head of from one ten-thousandth of an inch (00001") up to fourthousandths of an inch (0.004"). A counter mechanism at 98 connected with the adjusting wheel 96 has digit wheels thereon which indicate the selected increment of feed for the downfeed mechanism.

The downfeed mechanism may, if desired, include a stop device so that the downfeed of the wheel will stop at a predetermined position.

In operation, the truing tool is adjusted to an accurate position above the upper level of chuck 14 and which level can be taken as the zero position. As an example, dimension X might be 2.0000". With the truing tool thus set, the grinding wheel is brought into engageemnt with the truing tool and is rotated at slow speed and fed relative to the truing tool in the usual manner. The truing tool is reset when, and if, it wears.

Without changing the elevation of the wheel head at the end of the truing operation, sleeve 80 is retracted from engagement with gear 78 on shaft 76 and the counter mechanism consisting of disc 82 and counter 88 is adjusted until it also reads exactly 2.0000". The wheel head counter and the truing tool counter thus read exactly the same at this point.

The wheel head is now elevated to approximately 2.0100", which can be read off its counter, and the table is reciprocated With the workpiece W resting on chuck 14, passing to and from beneath the grinding wheel in the customary manner. The automatic downfeed mechanism 94 is now actuated and this causes the wheel head to feed downwardly in preset increments until the stop incorporated in the automatic downfeed mechanism operates and which has been previously adjusted to effective position, corresponding to the setting of the truing tool.

The truing tool may be set slightly higher than the finished level of the workpiece, say at 2.0008 inches so that after the final truing of the grinding wheel it can go into its final grinding without being elevated from its trued position. In the last mentioned case, the automatic downfeed will continue to lower the wheel until it reaches the level of 2.0000 inches.

From the foregoing, it will be appreciated that the present invention provides for the production of accurately sized finished workpieces without the necessity of any calculations on the part of the operator once the machine has been set up.

It will be understood that modifications and adaptations may be made in the structure and procedure, illustrated and described, and falling within the scope of the appended claims.

What is claimed is:

1. In a grinding machine having a frame: a wheel head supporting a grinding wheel and vertically slidable on said frame, a first screw in the frame engaging said wheel head and rotatable for moving the wheel head vertically on the frame, a table reciprocable on the frame beneath the wheel head and adapted for supporting a workpiece to engage said wheel from beneath, a truing tool on said table spaced from the region of the table which receives a workpiece and comprising a vertically moveable slide and carrying a truing element for engagement with said Wheel from beneath, a second screw in said truing tool engaging said slide and rotatable for moving the slide vertically, a first reversible drive motor connected to said first screw, a second reversible drive motor connected to 6 said second screw, means for selectively energizing said drive motors, a first counter, first means adjustably but 6 positively connecting said first counter to said first motor to be driven thereby, a second counter, and second means adjustably but positively connecting said second counter to said second motor to be driven thereby.

2. A grinding machine according to claim 1, in which said first and second means comprise first and second clutch means each having relatively indexable interengageable parts to permit adjustment of each counter relative to its pertaining screw.

3. A grinding machine according to claim 2, in which the connection of said first drive motor to said first screw includes reduction gearing such that one revolution of the said first drive motor produces movement of said wheel head, equal to of a predetermined standard dimensional unit.

'4. A grinding machine according to claim 3, in which said first counter includes a hand wheel directly coupled to said first motor via said first clutch and having 100 graduations in the form of digital figures carried on the periphery thereof so as to indicate movement of the wheel head in increments of movement of VlOOOO of said dimensional unit.

5. A grinding machine according to claim 4, in which said first counter includes decimal wheels having the first right hand one thereof coupled to said first hand wheel at a one to one drive ratio.

6. A grinding machine according to claim 5, in which said hand wheel has 20 finger holes distributed uniformly on one face thereof for manual actution of the hand wheel.

7. A grinding machine according to claim 6, in which said indexable parts of said first clutch have 100 uniformly spaced different positions of relative angular adjustment.

8. A. grinding machine according to claim 2, in which the connection of said second drive motor with said second screw includes reduction gearing such that one revolution of said second motor produces an increment of movement of said slide equal to of a predetermined standard dimensional unit.

9. A grinding machine according to claim 8, in which said second counter comprises a plurality of decimal wheels and the first right hand one thereof is coupled via said second clutch to said second motor.

10. A grinding machine according to claim 9, in which said parts of said second clutch have ten uniformly spaced different positions of relative angular adjustment.

11. A grinding machine according to claim 7, in which the connection of said second drive motor with said second screw includes reduction gearing such that one revolution of said second motor produces an increment of movement of said slide equal to of said dimensional unit, said second counter comprises a plurality of decimal wheels and the first right hand one thereof is coupled via said second clutch to said second motor, and said parts of said second clutch have ten uniformly spaced different positions of relative angular adjustment.

References Cited UNITED STATES PATENTS 2,520,868 8/1950 Whiting 5l165X 3,142,944 8/1964 Backer 51165 FOREIGN PATENTS 533,091 2/1922 France 51-165 HAROLD D. WHITEHEAD, Primary Examiner 

